Front end assemblies of excavating machines typically include a boom mounted on the main support frame of the machine, a hydraulic cylinder assembly operatively interconnecting the frame and the boom for raising and lowering the boom, a dipper stick pivotally connected to the free end of the boom, a hydraulic cylinder assembly interconnecting the boom and the dipper stick for pivoting the dipper stick relative to the boom, a bucket pivotally connected to the free end of the dipper stick and a hydraulic cylinder assembly operatively interconnecting the dipper stick and the bucket for curling and uncurling the bucket. For use in such assemblies in grappling various articles such as tree trunks, branches and brush, there has been developed an arm member, commonly referred to as a “thumb” which is adapted to cooperate with the bucket of such assembly for grappling articles therebetween. Generally, such thumbs have been connected to the underside of the dipper stick and have been provided with either a rigid strut interconnecting the dipper stick and the thumb to provide a thumb disposed at a fixed angle relative to the dipper stick or a hydraulic cylinder operatively interconnecting the dipper stick and thumb to permit the angle of the thumb relative to the dipper stick to be varied.
In the use of the later type of thumb assembly, it has been found that the location of the cylinder assembly below the dipper stick and adjacent the work area of the thumb member and the excavator bucket or other implement of the machine, often results in accidental damage to the rod member of the cylinder assembly and/or impairment of the seal between the rod and the cylinder members of the assembly. It thus is the principal object of the present invention to provide a thumb assembly for an excavating machine and the like, utilizing a hydraulic cylinder assembly for positioning the thumb member thereof, in which such cylinder assembly is protected from accidental damage of the rod member thereof and impairment of the seal between the rod and cylinder members thereof.